1 files changed, 118 insertions, 0 deletions
diff --git a/tools/libsigntools.py b/tools/libsigntools.py
new file mode 100644
index 0000000..a3f0bcc
--- /dev/null
+++ b/tools/libsigntools.py
@@ -0,0 +1,118 @@
+import sys
+import struct
+from hashlib import sha256, sha512
+
+def checksum_stdin(hashalg='sha256'):
+    if hashalg == 'sha256':
+        d = sha256()
+    elif hashalg == 'sha512':
+        d = sha512()
+    else:
+        return None
+
+    while True:
+        buf = sys.stdin.buffer.read()
+        if not buf:
+            break
+        d.update(buf)
+
+    return d.digest()
+
+def ssh_to_sign(namespace, hashalg, checksum):
+    if hashalg == 'sha256':
+        hashlen = 32
+    elif hashalg == 'sha512':
+        hashlen = 64
+    else:
+        return None
+    s = struct.pack('!6sI{}sII6sI{}s'.format(len(namespace), hashlen),
+                    b'SSHSIG',
+                    len(namespace), bytes(namespace, 'ascii'),
+                    0,
+                    6, bytes(hashalg, 'ascii'),
+                    hashlen, checksum)
+    return s
+
+# Adapted from https://stackoverflow.com/questions/65684414/how-to-use-ssh-keygen-ed25519-keys-for-encryption-in-python
+# Author: LJHW
+from base64 import b64decode
+from nacl.encoding import RawEncoder
+from nacl.signing  import SigningKey, VerifyKey
+class C25519:
+    # Adapted from https://gist.github.com/R-VdP/b7ac0106a4fd395ee1c37bfe6f552a36 sealing.py
+    # Author: Ramses https://github.com/R-VdP
+    __key_length = 32
+    __private_key_signature = b'\x00\x00\x00\x40'
+    __public_key_signature  = b'\x00\x00\x00\x20'
+
+    @classmethod
+    def __bytes_after(cls, signature, length, bytestr):
+        start = bytestr.find(signature) + len(signature)
+        return bytestr[start:start+length]
+
+    @classmethod
+    def __extract_signing_key(cls, private_data):
+        openssh_bytes = b64decode(private_data)
+        private_bytes = cls.__bytes_after(
+            cls.__private_key_signature,
+            cls.__key_length,
+            openssh_bytes
+        )
+        signing_key = SigningKey(seed=private_bytes, encoder=RawEncoder)
+        return signing_key
+
+    @classmethod
+    def __extract_verify_key(cls, public_data):
+        openssh_bytes = b64decode(public_data)
+        public_bytes = cls.__bytes_after(
+            cls.__public_key_signature,
+            cls.__key_length,
+            openssh_bytes
+        )
+        verify_key = VerifyKey(key=public_bytes, encoder=RawEncoder)
+        return verify_key
+
+    @classmethod
+    def __private_data_from_file(cls, file_name):
+        with open(file_name, 'r') as file:
+            contents = file.read()
+        contents = contents.split('\n')
+        private_data = ''
+        for line in contents:
+            if 'PRIVATE KEY' in line:
+                continue
+            if not line:
+                continue
+            private_data += line
+        return private_data
+
+    @classmethod
+    def __public_data_from_file(cls, file_name):
+        with open(file_name, 'r') as file:
+            contents = file.read()
+        contents = contents.split(' ')
+        # assert contents[0] == 'ssh-ed25519'
+        public_data = contents[1].strip(' ')
+        return public_data
+
+    @classmethod
+    def signingKey(cls, private_ed25519_file):
+        private_data = cls.__private_data_from_file(private_ed25519_file)
+        signing_key = cls.__extract_signing_key(private_data)
+        return signing_key
+
+    @classmethod
+    def verifyKey(cls, public_ed25519_file):
+        public_data = cls.__public_data_from_file(public_ed25519_file)
+        verify_key = cls.__extract_verify_key(public_data)
+        return verify_key
+
+    @classmethod
+    def privateKey(cls, private_ed25519_file):
+        signing_key = cls.signingKey(private_ed25519_file)
+        return signing_key.to_curve25519_private_key()
+
+    @classmethod
+    def publicKey(cls, public_ed25519_file):
+        verify_key = cls.verifyKey(public_ed25519_file)
+        return verify_key.to_curve25519_public_key()